Yarn winding control apparatus



March 22, 1966 J. R. BRAY ETAL YARN WINDING CONTROL APPARATUS 2 Sheets-Sheet 3 Filed April 15, 1963 T. w. Mc GLAUGHLIN United States Patent 3,241,779 YARN WINDING CONTROL APPARATUS John R. Bray, Pensacola, Fla, John L. Marshall, Jr.,

Flornaton, Ala., and Thomas 'W. McGlaughlin and George B. Price, Pensacola, and Robert D. Taylor, Milton, Fla., assignors to Monsanto Company, a corporation of Delaware Filed Apr. 15, 1963, Ser. No. 273,220 16 Claims. (Cl. 242--18.1)

The present invention relates to apparatus for controlling yarn being wound on bobbins or other packages, and more particularly to such apparatus for so winding yarn on packages that removal of the yarn from the package is facilitated.

In the yarn winding art, the yarn is supplied from any of several processes such as spinning, drawing, etc. and is wound onto a rotating bobbin. The yarn is simultaneously traversed parallel to the bobbin axis during the winding, to form layers on the bobbin. Certain difficulties have occurred upon attempting to remove the yarn over-end from the package. When the revolutions per minute (r.p.m.) of the bobbin during the winding process have some integral whole number relationship to the traversal rate, it may be seen that the pattern of yarn placed on the package is repeated, producing an effect called ribboning. If the traversals per minute areequal to some integral multiple of the r.p.m. of the bobbin, it may 'be seen that the yarn is repeatedly laid exactly on the yarn from the previous layer rather than being circumferentially displaced as is desirable, and the resulting package formation may be termed primary ribboning. If the traversals per minute is some odd multiple of half the revolutions per minute of the bobbin, secondary ribboning is produced, and so forth. When an attempt is made to remove the yarn from the bobbin over-end, as is conventional, there is a tendency for several layers to slide off the bobbin at once in regions containing ribbons. This effect is most severe for primary ribbons.

In most yarn processes, the yarn is handled at a substantially constant rate, and thus it is desirable for the take-up mechanism to drive the bobbin so as to wind up the yarn at a constant rate. This is readily achieved by driving the bobbin from its surface at a constant peripheral velocity. As the package size increases, the bobbin revolution rate decreases inversely proportional to its circumference. If the traversing mechanism operates at a constant rate, it may be seen that the ratio of traversals per bobbin revolution (hereinafter termed the traversal ratio) increases from an initial low value as the package size increases, producing the various types of ribboning as the rpm. passes through various values corresponding to integral sub-multiples and multiples of the traversing rate.

It has been found that the formation of ribbons can be prevented with simple equipment by so proportioning the initial traversing rate and the initial bobbin r.p.m. that the traversal ratio is just greater than some whole number ratio which would produce ribboning, such as 1/2, and varying the traversing rate so as to prevent attain ment of the next higher traversal ratio which would cause troublesome ribboning, such as 1/ 1. Advantageously, the traversing rate may remain constant until the next highest troublesome traversal ratio is approached, then is continuously decreased at a sufficiently rapid rate to prevent ribboning.

Accordingly a primary object of the invention is to produce a novel ribbon-free package from which yarn may be readily removed.

A further object is to provide apparatus for winding ribbon-free packages of the above character.

3,241,779 Patented Mar. 22, 1966 A further object is to provide control circuits for controlling the revolution rate of a shaft according to a pre-set pattern.

A further object is to produce improved timing circuits for general control applications.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

For a more complete understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a schematic perspective view of a draw winding apparatus according to the present invention,

FIGURES 2a, 2b and 2c are a sequence of developed plan views of bobbin surfaces showing successive yarn paths during the formation of certain common types of ribboning,

FIGURE 3 is a graph of bobbin rpm. and the traversing rate as a function of time,

FIGURE 4 is a schematic diagram of an exemplary control mechanism used in the FIGURE 1 system, and

FIGURE 5 is a schematic diagram of the timing circuit incorporated in the FIGURE 4 control system.

Referring now to FIGURE 1 there is shown an exemplary yarn processing apparatus incorporating yarn winding control according to the present invention. As shown therein, yarn 20 from a suitable source 22 is supplied through a traversing mechanism 24 to be wound on bobbin 26. Bobbin 26 is surface driven at a constant surface velocity from a constant speed drive assembly 27 including a drive roll 28 and a constant speed motor 29, whereby the yarn take-up speed remains constant.

As illustrated, source 22 may be the texturing operation disclosed in more detail in US. Patent 3,041,706 to I. E. Bromley et al., or may be any other conventional source of yarn such as a spinning machine.

Traversing mechanism 24 includes a grooved traverse roll 30 driven from a constant speed motor 32 through a controllable variable speed coupling clutch 34. The speed at which traverse roll 30 is rotated is controlled according to the present invention by a control circuit 36 as will be explained below in detail. As will be apparent to those skilled in the art, yarn 20 is passed through groove 38 in roll 30 and makes a complete traversal, axially across bobbin 26 and back to its starting point, when roll 30 completes one revolution with a groove 38 of the illustrated configuration.

Referring now to FIGURES 2a, 2b and 20 there are shown developed plan views of the entire circumference of bobbin 26, illustrating the paths traversed by yarn 20 during the formation of exemplary types of ribboning.

Referring now to FIGURE 2a, there is shown a primary ribbon, wherein the traversal rate is exactly synchronized to the revolution rate of bobbin 26 so that yarn 20 makes one complete traversal for each revolution of bobbin 26 (traversal ratio equals unity). In this type of primary ribboning, each layer of yarn is laid directly on top of the preceding layer in parallel relationship so that the yarn accumulates in a single path around the bobbin.

A secondary ribbon is illustrated in FIGURE 2b, wherein the yarn 20 completes one traversal in the time required for bobbin 26 to make two complete revolutions (traversal ratio equals 1/2). Thus alternate layers applied to the bobbin are parallel and follow the same path. Secondary ribboning is not quite so severe in its adverse effects as the primary ribboning illustrated in I FIGURE 2a, but nonetheless gives difficulty when an attempt is made to remove the yarn over-end.

FIGURE 20 illustrates a tertiary ribbon for-med when the bobbin revolutions per minute are three times the traversal rate (traversal ratio equals 1/ 3). As may be seen on inspection of FIGURE 20, each third layer placed on bobbin 26 will be identical and aligned with a previous layer. Tertiary ribboning, while not desirable, is not so troublesome to yarn removal as the primary and secondary ribboning.

Referring now to FIGURE 3 there is illustrated a graph of bobbin r.p.m. and the traversing rate as a function of time, drawn to the same scale. As may be seen from FIGURES 1 and 3, if yarn 20 is supplied to bobbin 26 at a .constant rate, the bobbin speed will decrease according to the curve 40 since bobbin 26 is driven at a constant peripheral speed. It has been discovered that primary and secondary ribboning such as is illustrated in FIGURES 2a and 2b may be avoided by choosing an initial constant average traversing rate which is slightly greater than that required to complete a traversal in two bobbin revolutions, and maintaining this average traversal rate constant until the bobbin rate of rotation has slowed sufficiently that a traversal is made in slightly less than one complete bobbin revolution, and then decreasing the traversal rate at a sufiiciently fast rate of decrease such that the traversals always occur in less than one bobbin revolution. This is graphically illustrated in the dotted line 42, which shows the traversal rate per minute as a function of time. As illustrated in FIGURE 3, it has further been found that the deleterious efiects of the various tertiary, etc., ribboning which occurs between the primary and secondary ribboning may be avoided by imposing on the average traversal rate shown in dotted line 42 a continual short term variation about the average rate, such that the traversal rate is as illustrated in the solid line 44. Actually the period of each short term variation will be much shorter than that illustrated, as will be discussed below. The control mechanism for providing the operation illustrated in FIGURE 3 is shown in FIGURES 4 and 5.

Referring now to FIGURE 4, the basic control circuit 36 for controlling clutch 34 in FIGURE 1 is illustrated, and includes a thyratron tube 46 energized from an A.C. source 48 through the secondary winding of a transformer 50 connected between the plate 52 of the thyratron to the upper end of the clutch coil 54, the opposite end of coil 54 being grounded. A diode 56 is shunted across coil 54 to prevent the application to the thyratron of the high voltage counter-EMF. generated when the flux field in coil 54 collapses. The cathode 58 of the thyratron may be grounded. As will be apparent to those skilled in the art, the degree of coupling in clutch 34 is dependent upon the average DC. current flowing in coil 54, which in turn depends upon the biasing potential appearing on the grid 60 of tube 46. According to the present invention, this biasing potential appearing on grid 60 is controlled as a function of time according to a preset pattern so that the traversal speed follows the solid line curve 44 in FIGURE 3.

The control circuitry illustrated in FIGURE 4 includes several individual electric signals which are summed or added to produce the required composite biasing potential on grid 60. These include a first D.C. feedback signal proportional to the speed of the clutch output shaft, which first signal upon increasing reduces the output speed, a second signal which is cyclic in nature, and a third DC. signal which is opposed to the first DC. signal and which is varied as a function of time to control the traverse speed. In addition, a small A.C. rider voltage is superimposed on the grid control signal to extend the range of control of firing angle of the thyratron 46.

The first signal is derived from a tachometer generator 62, which is driven by clutch 34. Generator 62 produces an A.C. signal on its terminals 64 and 66 which is proportional to the traversal rate. This A.C. signal on terminals 64 and 66 is applied through a variable resistor 68 to the primary winding of a transformer 70. The secondary winding of transformer 70 is connected through a diode 72 to a voltage divider 74, and filter capacitor 76 is shunted across voltage divider 74. Thus the A.C. output of tachometer generator 62 is rectified by diode 72 and is applied as a first D.C. biasing voltage appearing across voltage divider 74 to control the voltage on the grid 60 according to the traversal rate. The wiper 78 of the voltage divider 74 is connected to one end of a further voltage divider 80, the wiper 82 of which is connected to grid 60.

The A.C. rider wave is superimposed on the direct volt age appearing on wiper 82 in order to extend the range of control over thyratron 46. Thus a transformer 84 having its primary winding connected to source 48 has one end of its secondary winding 86 connected through a capacitor 88 to wiper 78, the opposite end of secondary winding 86 being connected to the opposite end of voltage divider 80. The phase of the A.C. voltage appearing across voltage divider is shifted 90 degrees by capacitor 8-8 from the applied voltage from source 48. As will be understood by those skilled in the art, this permits precise control of the triggering of thyratron 46 at any point through the entire possible 180 degrees of conduction of thyratron 46, permitting much closer and more accurate control.

Still referring to FIGURE 4, a continuously running motor 90 drives a heart-shaped cam 92, the cam follower of which continuously drives the movable arm of variable resistor 68, whereby the tachometer voltage output supplied to diode 72 is continuously varied between given limits. Cam 92 may be rotated at about one to ten r.p.m. This provides the cyclic signal, the function of which will be further explained below.

The third direct current control signal is supplied to grid 60 from the timing circuit 94, by an output conductor 96 which is connected to one end of voltage divider 74. Timing circuit 94 is illustrated in FIGURE 5 and includes a first timer 98 which after a given time delay energizes a pulse timing circuit 100. The output of pulsing circuit 100 drives a particular control mechanism 102 to slowly decrease the positive output voltage produced. on conductor 96 from an initial preset value. As illustrated, alternating current power is supplied to timing circuit 94 on a conductor 104 through a start switch 106 to the ungrounded side of timer 98. Timer 98 closes a contact 108 after a fixed interval of time. Closing of contact 108 supplies A.C. from conductor 104 through a transformer 110 to a full wave bridge rectifier 112. As illustrated, the negative side of bridge 112 is grounded, and the rectified positive voltage output is supplied to a conductor 114. A filter condenser 116 is shunted between conductor 114 and ground to remove the ripple.

A series circuit including a resistor 118 and a Zener diode 120 provides a constant supply voltage on conductor 122. A unijunction transistor 124 has its emitter electrode 126 connected through resistor 128 to supply conductor 122. A resistor 130 connects the second base electrode of unijunction transistor 124 to supply conductor 122 while resistor 132 connects the first base electrode to ground. A capacitor 134, connected between the emitter electrode 126 and ground, forms with resistor 128 a time constant circuit which determines the firing rate of the unijunction transistor to a predetermined value. Unijunction transistor 124 thus provides a series of unidirectional, positive output pulses across resistor 132, which pulses are uniform in amplitude and timing.

A silicon controlled rectifier 138 has its cathode electrode 140 connected to ground, and its anode electrode 142 connected through the winding of a relay 144 and a resistor 146 to DC supply conductor 114. A diode 148 connects the second base electrode of unijunction transistor 124 to the gate electrode 150 of silicon controlled rectifier 138, to prevent reverse or leakage electron flow through resistor 132 and gate electrode 150 to the anode 142. A capacitor 152 is connected between anode electrode 142 and ground to control actuation of relay 144, as will be explained.

Thus it may be seen that unijunction transistor 124 produces a series of positive output pulses on its second base electrode under the control of the time constant circuit including resistor 128 and capacitor 134. These positive output pulses are applied through diode 148 to the gate electrode 150 of rectifier 138, and cause switching of rectifier 138 to its conducting state on the occurrence of each pulse.

The exemplary control mechanism 102 includes a stepper motor 153 which requires alternate pulses of opposite polarity to be applied to its ungrounded terminal 154 for its operation. Such a stepper motor 153 is available as the 18100 Series motor from the A. W. Haydon Co., Waterbury, Connecticut. Pulse circuit 100 is adapted to provide such opposite polarity pulses, spaced apart at the proper intervals.

Relay 144 includes a movable contact arm 156 attached 7 to the relay armature, a grounded contact 158, and a contact 160 connected to DC. supply conductor 114. Thus contact 156 is connected to conductor 114 when relay 144 is energized, and is grounded when relay 144 releases, and accordingly has impressed thereon a square wave signal. Contact arm 156 is connected through series capacitor 162 to terminal 154 on stepper motor 153. A shunt resistor 164, connected between terminal 154 and ground, forms with capacitor 162 a differentiating circuit, so that a positive spike signal is applied to motor 153 when relay 144 energizes, and a negative spike signal is applied to motor 153 when relay 144 releases.

The interval between occurrence of a positive spike signal and the succeeding negative spike signal is controlled by capacitor 152 in conjunction with resistor 146. It is initially assumed that both unijunction transistor 124 and silicon controlled rectifier 138 are non-conductive, capacitors 134 and 162 are discharged, and capacitor 152 is charged to the full potential of conductor 114. No current will then flow in relay 144, and its arm 156 will be grounded.

The voltage across capacitor 134 will rise, as determined by the time constant of resistor 128 and capacitor 134, until the emitter current increases to the negative resistance region, at which time transistor 124 triggers into conduction. This produces an output pulse across resistor 132, the output pulse having a duration determined by the time constant of capacitor 134 and resistor 132, i.e., the output pulse lasts until capacitor 134 discharges through resistor 132. In general, the output pulse appearing across resistor 132 will be of very brief duration.. These output pulses, as noted above, are applied through diode 148 to gate electrode 150 of silicon controlled rectifier 138, switching silicon controlled rectifier 138 to its conducting state.

The resistance of resistor 146 and the impedance of relay 144 are sufiiciently high to limit the current therethrough to a level below the minimum required to maintain conduction in diode 148. When rectifier 1138 conducts, capacitor 152 is discharged through rectifier 138, until the total current suppliedby capacitor 152 and through relay 144 falls below the level required to maintain conduction in the rectifier, whereupon rectifier 138 reverts to its non-conducting state. Capacitor 152 is then recharged up to the potential on conductor 114 by the current through resistor 146 and relay 144, which current is suflicient to hold the relay energized. Thus the time during which relay 144 is energized is determined by the impedances of the relay, resistor 146, and capacitor 152, rather than merely by the duration of the output pulse appearing across resistor 132. This produces a square wave on movable arm 156 of the required duration so that the negative spike voltage produced in the differentiating circuit by the trailing edge thereof will be delayed sufiiciently for the requirements of stepper motor 153.

A voltage divider 166 is connected between a positive supply terminal 168 and ground. The wiper arm 170 of voltage divider 166 is electrically connected to output conductor 96, and is driven toward the grounded end of voltage divider 166 by motor 153. Thus as motor 153 rotates, the output signal on conductor 96 becomes less positive. Of course, suitable gear trains may be interposed between the output shaft of motor 153 and wiper arm 170, and resetting means may be provided to reset wiper arm 170 to a given initial position on voltage divider 166 at the beginning of each cycle of operation, if desired.

The operation of the apparatus will now be summarized with reference to FIGURES 1, 3, 4 and 5. Referring to FIGURE 1, yarn 20 is supplied through a grooved roll 30 to the bobbin 26 where it is taken up. Bobbin 26 is surface driven at a constant peripheral speed by drive roll 28. As the yarn 20 builds up on bobbin 26, the angular velocity of the bobbin decreases. The traversal rate of yarn 20 across the surface of bobbin 26 is initially set by adjustment of voltage dividers 74 (FIG- URE 4) and 166 (FIGURE 5) such that the traversal ratio is just greater than some whole number ratio which would produce troublesome ribboning, such as 1/ 2.

Referring to FIGURE 5, start switch 106 is closed, actuating timer 98, which begins to run through its timed cycle. After a given time delay, which preferably would last until just before the traversal ratio reaches the next higher value which would cause troublesome rib-boning, such as 1/ 1, timer 98 closes its contact 108. This would occur when the circumference of the package had approximately doubled. An exemplary delay period for timer 98, for a commercially produced yarn package, may be of the order of magnitude of a few hours, depending on the take-up speed and the initial bobbin diameter.

Closing of contact 108 energizes pulse timing circuit and begins the operation of motor 153. Unijunction transistor 124 produces a series of short duration positive pulses, each of which is applied through diode 148 to gate electrode 150 of silicon controlled rectifier 138. Each such pulse triggers rectifier 138 into its conducting state. Capacitor 152 then discharges through rectifier 1138 until the current flow through rectifier 138 falls to a sufficiently low level that rectifier 138 reverts to its non-conducting state. Capacitor 152 is then recharged to the voltage appearing on conductor 114 through resistor 146 and the winding of relay 144. The charging current of capacitor 152 is sufiiciently great to maintain relay 144 energized for an appreciable period of time after rectifier 138 has become non-conducting. This insures that a positive pulse or square wave applied to movable arm 156 of relay 144 is of a sufficient duration to accommodate the requirements of motor 153. The square wave signal is differentiated by capacitor 162 and resistor 164, so that the signal actually applied to motor 153 is a positive spike signal produced when relay 144 energizes and a negative spike signal produced when relay 144 releases.

The signals of alternate positive and negative pulses applied to motor 153 drives wiper arm on voltage divider 166 in the direction to decrease the positive potential on output conductor 96 from the initial value which it had before timer 98 closed its contact 108 to an ever decreasing value. As shown in FIGURE 3, the rate of decrease in positive potential on output conductor 96 should be suificient so that traversing mechanism 24 drives or traverses yarn 20 at a decreasing rate approximately equal to or slightly greater than the decreasing revolution rate of bobbin 26.

As shown in FIGURE 4, the decreasing positive potential on conductor 96 after timer 98 has actuated its contact 108, produces a more negative signal on control grid 60 of thyratron tube 46. This results in conduction of thyratron 46 of less and less of its possible degrees, and reduces the amount of direct current flowing in clutch coil 54. Referring to FIGURE 1, reduction in current in coil 54 slows down the rotation of groove roll 30, reducing the traversal rate.

The operation as just described refers to controlling the traversal rate according to the dotted line 42 in FIGURE 3. It has been found to be advantageous to continually vary the traversal rate about the average value shown in dotted line 42, so that the actual traversal rate is as depicted in solid line 44. Such operation is produced by the continually energized motor 90 illustrated in FIGURE 4. As briefly described above, motor 90 drives the heartshaped cam 92 at a constant rate such as between one and ten rpm. The cam follower of cam 92 continually drives the movable arm of variable resistor 68 back and forth over resistor 68 so that the tachometer voltage output supplied through transformer 70 to diode 72 is continually varied in its amplitude over a limited range at a cyclic rate of approximately 1 or 2 cycles per minute. This cyclic signal, applied to grid 60 superimposed on the ordinary tachometer signal and the timing circuit output signal appearing on conductor 96, varies the clutch output speed as illustrated by the solid line 44 in FIGURE 3. In a particular embodiment, the clutch output speed was varied in amplitude rpm. about its average speed (about 940 rpm. before timer 98 actuates timing circuit 100), at a rate of 2 cycles per minute.

The cyclic variation in traverse rate greatly reduces the severity of the ribboning produced Within the range of traversal ratios permitted by timing circuit 94. For example, if the initial traversal ratio is just greater than 1/2 and if timer 98 times out just before the traversal ratio reaches unity, the range of traversal ratios will include 2/3 (tertiary ribboning) and 3/4 (quaternary ribboning). With the cyclic variation in traverse rate, however, the traversal ratio is rapidly passed through these ratios and does not remain at any one ratio long enough for a troublesome ribbon to build up on the bobbin.

From the above description and the enclosed drawings it may be seen that a novel ribbon free package has been provided, from which yarn may be readily removed. The disclosed apparatus for producing such yam packages may be readily made with minimum modifications of existing yarn winding apparatus. The system features a constant yarn take-up velocity, so that it is suited to any yarn process having constant yarn delivery speed. The particular control circuits disclosed for controlling the stepper motor 153, including the various delay features made possible by the coaction of capacitor 152 with its current actuated devices (silicon controlled rectifier 138 and relay 144) provides for simple control of motor 153, and is capable of other and broader applications.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are eificiently attained and, since certain changes may be made in the described product, and in the apparatus set forth without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

1. Winding apparatus for winding yarn on a bobbin comprising in combination:

(a) a source supplying yarn at constant velocity to said bobbin,

(b) drive means for driving said bobbin at a constant peripheral velocity,

(c) a traversing mechanism for repetitively traversing said yarn axially along the surface of said bobbin during windup,

(d) and traversal control means for driving said traversing mechanism at a constant average initial repetition rate less than the initial revolution rate of said bobbin for a period of time. until the bobbin revolution rate decreases to near the average traversalrepetition rate, and for then decreasing the average traversal repetition rate sufliciently rapidly that the average traversal repetition rate remains lower than the revolution rate.

2. The apparatus defined in claim 1, wherein said traversal control means comprises:

(a) first means for decreasing the average repetition rate of said traversing mechanism,

(b) and time delay means for preventing the operation of said first means for a preset interval of time.

3. Winding apparatus for winding yarn on a bobbin comprising in combination:

(a) a source supplying yarn at constant velocity to said bobbin,

(b) drive means for driving said bobbin at a constant peripheral velocity,

(0) a traversing mechanism for traversing said yarn axially along the surface of said bobbin during windup,

(d) and traverse control means for maintaining the traversal ratio between the values of l/ 2 and unity during a time interval sufficiently long for the bobbin revolutions per minute to decrease from a given initial value to a value less than one-half of said initial value.

4. A circuit for maintaining current fiow above a particular level for a given minimum interval of time in a current operated device which requires at least said particular level of current flow for operation, said circuit comprising in combination:

(a) first and second direct current power supply conductors,

(b) impedance including said current operated device, said impedance having a first terminal connected to said first power supply conductor and having a second terminal,

(c) a capacitor connected between said second terminal and said second power supply conductor,

(d) and switching means for initiating current flow in said current operated device, said switching means having a first switch terminal connected to said second terminal and a second switch terminal connccted to said second power supply conductor.

5. The circuit defined in claim 4, wherein said switching means is current actuated and wherein said current operated device requires less holding current than said switching means.

6. The combination defined in claim 4, wherein said switching means remains in the conductive state until the current therethrough drops below a given level.

7. The combination defined in claim 6, wherein said impedance limits the current flow in said current operated device to a level below said given level and above said particular level.

8. A circuit for maintaining current flow in a relay for a given minimum interval of time, said circuit comprising in combination:

(a) impedance including a relay winding connected in series with a capacitor between first and second direct current power supply conductors,

(b) and switching means connected in series with said relay Winding and in parallel with said capacitor for momentarily discharging said capacitor.

9. The circuitry defined in claim 8, wherein said switching means is a silicon controlled rectifier having a minimum holding current greater than the minimum holding current of said relay winding.

10. A circuit for producing positive and negative pulse signals spaced apart a minimum period of time comprising:

(a) impedance including a relay winding connected in series with a capacitor between first and second direct current power supply conductors,

(b) switching means connected across said capacitor for momentarily discharging said capacitor,

() contacts on said relay for connecting a signal conductor to a first potential when said relay is energized and to a reference potential when said relay is de-energized,

(d) and a differentiating circuit for ditferentiating the potentials applied to said signal conductor.

11. The circuit defined in claim 10, wherein said differentiating circuit comprises a series capacitor and a shunt resistor.

12. Winding apparatus for winding yarn on a bobbin, comprising in combination:

(a) a source supplying yarn at constant velocity to said bobbin,

(b) drive means for driving said bobbin at a constant peripheral velocity,

(c) a traversing mechanism for repetitively traversing said yarn axially along the surface of said bobbin during windup,

(d) and traversal control means for driving said traversing mechanism at a constant average initial repetition rate less than the initial revolution rate of said bobbin for a period of time until the bobbin revolution rate decreases to near the average traversal repetition rate, and for then decreasing the average traversal repetition rate sufiiciently rapidly that the average traversal repetition rate remains lower than the revolution rate, said traversal control means comprising cyclic control means for continually varying the traversal rate about its average value.

13. Winding apparatus for winding yarn on a bobbin,

comprising in combination:

(a) a source supplying yarn at constant velocity to said bobbin,

(b) drive means for driving said bobbin at a constant peripheral velocity,

(c) a traversing mechanism for repetitively traversing said yarn axially along the surface of said bobbin during windup,

(d) and traversal control means for driving said traversing mechanism at a constant average initial repetition rate less than the initial revolution rate of said bobbin for a period of time until the bobbin revolution rate decreases to near the average traversal repetition rate, and for then decreasing the average traversal repetition rate sufficiently rapidly that the average traversal repetition rate remains lower than the revolution rate, said traversal control means comprising cyclic control means which varies the traversal rate about its average value at a cyclic rate of greater than one cycle per minute.

14. The apparatus defined in claim 13, wherein said cyclic control means cyclically varies the amplitude of the traversal rate more than 1% of its average value.

15. Winding apparatus for winding yarn on a bobbin, comprising in combination:

(a) a source supplying yarn at constant velocity to said bobbin,

(b) drive means for driving said bobbin at a constant peripheral velocity, (0) a traversing mechanism for repetitively traversing said yarn axially along the surface of said bobbin during windup,

(d) and traversal control means for driving said traversing mechanism at a constant average initial repetition rate less than the initial revolution rate of said bobbin for a period of time until the bobbin revolution rate decreases to near the average traversal repetition rate, and for then decreasing the average traversal repetition rate sufiiciently rapidly that the average traversal repetition rate remains lower than the revolution rate, said traversal control means comprising:

(1) a controllable variable speed electrical clutch coupling said traversing mechanism to a motor,

(2) first means for producing differentiated signals on a signal conductor,

(3) clutch energizing means for supplying energizing current to said clutch,

(4) clutch controller means for reducing the energizing current supplied to said clutch in response to the presence of differential potentials on said signal conductor,

(5) and time means for preventing the operation of said first means for said period of time.

16. The apparatus defined in claim 15, wherein said first means for producing differentiated signals comprises:

(a) impedance including a relay winding connected in series with a capacitor between first and second power supply terminals,

(b) switching means connected across said capacitor for momentarily discharging said capacitor,

(c) contacts on said relay for connecting said signal conductor to a first potential when said relay is energized and to a reference potential when said relay is de-energized,

(d) and a difierentiating circuit for differentiating the potentials applied to said signal conductor.

References Cited by the Examiner UNITED STATES PATENTS 2,763,824 9/1956 Bacheler 242-181 X 2,862,672 12/1958 Pool et al. 242l8.1

OTHER REFERENCES MERVIN STEIN, Primary Examiner.

RUSSELL c. MADER, Examiner. 

1. WINDING APPARATUS FOR WINDING YARN ON A RIBBON COMPRISING IN COMBINATION: (A) A SOURCE SUPPLYING YARN AT CONSTANT VELOCITY TO SAID BOBBIN, (B) DRIVE MEANS FOR DRIVING SAID RIBBON AT A CONSTANT PERIPHERAL VELOCITY, (C) A TRAVERSING MECHANISM FOR REPETITIVELY TRAVERSING SAID YARN AXIALLY ALONG THE SURFACE OF SAID BOBBIN DURING WINDUP, (D) AND TRAVERSAL CONTROL MEANS FOR DRIVING SAID TRAVERSING MECHANISM AT A CONSTANT AVERAGE INITIAL REPETITION RATE LESS THAN THE INITIAL REVOLUTION RATE OF SAID BOBBIN FOR A PERIOD OF TIME UNTIL THE BOBBIN REVOLUTION RATE DECREASES TO NEAR THE AVERAGE TRAVERSAL REPETITION RATE, AND FOR THEN DECREASING THE AVERAGE TRAVERSAL REPETITION RATE SUFFICIENTLY RAPIDLY THAT THE AVERAGE TRAVERSAL REPETITION RATE REMAINS LOWER THAN THE REVOLUTION RATE. 